This invention relates to a method of processing a sample including an etching step, and to an apparatus for carrying out such a method, and more particularly to a processing method and apparatus which is suitable for processing a sample in the manufacture of a semiconductor device or other device including miniaturized components.
A sample such as a semiconductor device substrate is etched by a chemical solution or by plasma, for example. Sufficient care must be paid to corrosion protection of the sample after etching processing.
A corrosion-proofing technique after etching is disclosed, for example, in U.S. Pat. No. 4,487,678. This technique subjects a resist film, after etching by plasma inside an etching chamber, to removal in a second plasma processing chamber connected to the etching chamber. The second plasma treatment removes chlorine compounds which are corrosive components remaining in the resist film or on the etched surface. It is also known to heat the sample after etching to at least 200xc2x0 C. in order to promote evaporation of chlorides that are residual corrosive components. Japanese Laid-Open Patent Publication No. JP-A-61-133388 discloses a method in which a sample after plasma etching is transferred to a heat-treating chamber in which hot air is blown on it to remove corrosive compounds. Thereafter the sample is washed with water and dried.
The present applicants have found that these aforementioned techniques involve the problem that sufficient corrosion-proofing performance cannot be obtained, at least for certain kinds of samples.
For instance, the techniques described above are believed effective in some cases for corrosion-proofing of a single metallic film such as an aluminum (Al) wiring film. However, they fail to provide a sufficient corrosion-proofing effect after etching of a sample having metals having mutually different ionization tendencies such as films of Al, Cu, W, Ti, Mo, etc. and their alloys or laminates, e.g., as a laminate wiring structure.
With the remarkable progress in miniaturization in recent years, wiring films have been more and more miniaturized, and an Alxe2x80x94Cuxe2x80x94Si alloy film having a few percent of Cu content in place of the conventional Alxe2x80x94Si alloy film and a laminate structure of the Alxe2x80x94Cuxe2x80x94Si alloy film and a refractory metal film such as titanium tungsten (TiW), titanium nitride (TiN) and molybdenum silicon (MoSi) film for reducing contact resistance have gained wide application as a wiring film in order to prevent breakage due to electromigration and stress migration. In such a wiring film structure, ionization tendencies of Al and Cu, W, Ti, Mo or the like are different so that a battery action develops due to water acting as an electrolyte, and corrosion of the wiring film is accelerated by so-called xe2x80x9celectrolytic corrosionxe2x80x9d. Even if corrosive materials generated by etching are removed by utilizing plasma at a high temperature of 200xc2x0 C. or above, corrosion occurs due to the effect of moisture on remaining corrosive compounds within some minutes or several hours after the sample is withdrawn into the atmosphere.
As a countermeasure of the above xe2x80x9celectrolytic corrosionxe2x80x9d problem, there has been proposed, as disclosed in Japanese Laid-Open Publication No. Hei 2-2242233, a sample processing apparatus comprising means for processing a sample (e.g., etching processing the sample), means for post-processing a processed sample, the post-processing means utilizing a plasma, means for wet-processing a processed sample processed through the plasma post-processing means, and means for dry-processing a processed sample which has been processed through the wet-processing means. Corrosion of the sample after the etching processing, irrespective of the kind of the sample, can be prevented effectively utilizing this sample processing apparatus.
However, since the sample processing apparatus shown in the above-discussed Japanese Laid-Open Publication No. Hei 2-2242233 comprises a single means for wet-processing the sample processed through the plasma post-processing means, the through-put is limited; moreover, when the wet-processing time is lengthened, such that the corrosion-preventing effect is improved, a further problem is caused that the through-put is even further lowered.
It is an object of the present invention to provide a sample processing method and apparatus which can prevent sufficiently corrosion of a sample after etching irrespective of the kind of sample.
Another object of the present invention is to provide a sample processing method and apparatus wherein through-put of the processing can be increased without a loss in the corrosion-preventing effect.
The above and other objects of the present invention and novel features will be clear from the description of the present specification and also from the attached drawings. This description and drawings are not limiting of the invention, the scope of the present invention being defined by the claims.
Within the invention disclosed in the present application, an outline of a representative example will be explained in the following. This representative example illustrates, and is not limiting of, the present invention.
According to one aspect of the present invention, a sample processing apparatus comprises means for processing a sample (e.g., an etching processing means, such as a plasma etching means), means for plasma post-processing a sample, that has been processed through the processing means, under a reduced pressure condition, means for wet-processing a sample that has been processed through the plasma post-processing means and means for dry-processing a sample that has been processed through the wet-processing means. This aspect of the present invention includes techniques for using this apparatus.
According to a further aspect of the present invention, a sample processing apparatus can include means for processing a sample (e.g., an etching processing means, such as a plasma etching means); a plurality (e.g., two) of wet-processing means, for processing samples passed through the sample processing means; and, e.g., means for dry-processing a sample that has been passed through the wet processing means. This aspect of the present invention also includes methods of using this apparatus.
The plurality of wet processing means can be used in series, or can be used in parallel (that is, samples can alternatively be passed to one or another of the wet-processing means, e.g., to an unoccupied wet-processing means) to decrease processing time. In such use of wet-processing means in parallel, there is overlapping use of the wet-processing means. Through parallel use of the wet-processing means, at least two of the wet-processing means are used simultaneously on different samples, thereby decreasing total processing time for a plurality of samples, particularly where the wet-processing takes a longer time to perform than, e.g., the sample processing in the sample processing means.
As a further aspect of the present invention, the wet-processing can include a plurality of treatments (e.g., a chemical treatment in, e.g., an alkaline or acidic solution, together with a water rinse of a sample).
In parallel passing of the samples through the wet processing means, a plurality of wet processing treatments can be performed at a single wet processing means (station). In series passing of samples through the plurality of wet-processing means (stations), a single wet-processing treatment can be performed at each means; however, a plurality of wet-processing treatments can also be provided at each means.
According to the present invention, the samples can also be subjected to additional treatment (means) for removing residual corrosive compounds, formed, e.g., as a result of the sample processing (e.g., plasma etching), this additional treatment being performed between the sample processing and wet processing. This additional treatment can be a plasma processing, e.g., under a reduced pressure.
Passing of samples through the various processing stations can be controlled by a controller (e.g., a personal computer), as would be known by the ordinary worker in the art. This controller can be used to provide series or parallel passing of samples through the wet-processing means.
According to the present invention, within a series of processing steps comprising a step for processing a sample, a step for plasma post-processing a processed sample under a reduced pressure condition, a step for wet-processing a processed sample of the plasma post-processing means and a step for dry-processing a processed sample of the wet-processing means, in the wet-processing step (which could cause lowering of the through-put in the processing) plural wet-processing means are provided so that the lowering of the through-put in the processing does not occur; and, irrespective of the kind of the sample, it is possible to prevent effectively corrosion of the sample after the etching process.
In this description, a plasma treatment step, after sample processing (e.g., plasma etching), is called post-processing, the liquid treatment step is called wet-processing, and the drying step is called dry-processing, for convenience.
In the invention, a sample is etched by use of plasma. After etching, the sample is post-processed by plasma post-processing means by utilizing plasma under a reduced pressure. The post-processed sample from the plasma post-processing means is wet-processed by wet-processing means. The wet-processed sample is dry-processed by dry-processing means. Since post-processing using plasma and wet-processing are both carried out, the corrosive materials that occur due to etching can be removed sufficiently from the etched sample. Therefore, even when the etched sample is withdrawn into external air, for example, its corrosion can be sufficiently prevented irrespective of the kind of sample. Moreover, treatment time can be reduced.